The overall objective of this study is to continue the biochemical morphological, and immunological analyses of the plasma membranes of the ocular lens. Among the questions to be addressed are: A determination of the developmental and aging changes in the lipid composition of the lens fiber cell plasma membranes; A determination of the protein-lipid interactions of the lens gap junction protein will be sought as a basis for a delineation of the lipid requirements to its structure and functioning; A determination of the biochemical compositional (protein, lipid) basis of topographical heterogeneity in the lens fiber plasma membrane; The presence of Na-K-ATPase in lens fiber membranes will be investigated by immunological methods, and a study will be conducted on its developmental and regional distribution in normal lenses. The age-related conversion of MP26 to MP22 in human lenses will be specifically addressed through a developmental analysis of their cyanogen bromide-derived fragments. An attempt will be made to identify the structural domain of the protein involved in the conversion. The specific aims of the proposed project will extend our knowledge and understanding of the development, morphology, and composition of the plasma membrane of lens fiber cells. The biochemical definition and study of structural and functional membrane heterogeneity in the lens fiber will increase our understanding of the cytological and molecular architecture of its plasma membrane. The overall objective of the project is to provide a basis upon which to test the role which fiber plasma membranes play in lens function (transparency, accomodation) and in the development of the cataractous state.